The invention generally relates to hook assemblies comprising an ejector for releasing a load suspended in the hook assembly; the invention particularly refers to such a hook assembly comprising a lifting eye bolt and a hook positioned at opposite ends of a body as well as a combined ejector and latch device rotatably connected to the hook and adapted, in a first position, to detend a load suspended in the hook and, upon shift to another position, to release the load from the hook.
Load hooks have been known for a long time which are provided with a latch rotatably arranged at the hook opening permitting insertion of the lifting implement in the hook but preventing unintentional release therefrom. A further development of the load hook comprising a latch is a security hook, such as Gunnebo Original BK, in which the lifting eye and the latch are integrated and are articulately connected to the hook, the construction being such as to automatically close the latch when the security hook is loaded, opening being prevented until the load is to be released from the hook and a latch is operated. The main purpose of the hooks mentioned above is to prevent unintentional release of a supported load if the load during lifting unintentionally comes into contact with some object causing the hook accidentally to be relieved from the load; in this respect the hooks in question have been working satisfactorily on several fields of use. The drawback inherent in these hooks, however, resides in that in every case manual operation and uncoupling is required, the uncoupling in particular being a dangerous moment in connection with certain handling of goods in the industry, stevedore work and on the building field, etc. where the load, for example, comprises a number of heavy, loose parts which, when released, may start moving and hurt the operator. From U.S. Pat. No. 3,918,758 a lifting hook is known intended to solve the last-mentioned problem by rotatably providing thereon a combined ejector and latch which is manually operable from a place securely spaced from the load. The function is such that the operator, after having relieved the load from the hook by placing the load on the ground, pulls a line or rope attached to the ejector and thereby causes the ejector to turn in such a way that the load is released from the hook while at the same time the latch uncovers the opening of the hook. The important disadvantage of this known hook resides in that it is practically impossible to use in certain situations when the line for some reason can not freely be extended to the place of the operator. Other disadvantages of the known hook reside in the fact that it has protuding portions which during lifting tend to be entangled with other objects in the environment and that, due to some constructive details, no secure function can be guaranteed after an extended time of use, in particular outdoors when the hook constantly is exposed to wind and weather.
Recently such releasable hook assemblies have been further developed by being provided with remotely controlled operating means for the ejector and latch unit. In this connection both electric and hydraulic motors have been used as operating means, remote control having been performed by means of radio signals or via control conduits. While such additionally developed hook assemblies as a rule function satisfactorily, they are comparatively expensive in manufacture and, in addition, there is always a risk of faulty function by a faulty control signal, for example due to the human factor, being supplied to the control means, or due to damage done to the control conduits and, in the case of radio control, due to the triggering of a faulty function under the action of other radio transmitters. From, for example, Swedish patent specification No. 226 020 and Finnish published and printed specifications Nos. 61015 and 62516 hook assemblies are known in which a coupled load after having being placed on the ground is released by rotating the entire hook about a pivot so that the hook opening is directed downwardly. In addition to the fact that such solutions, in particular in hook devices used for heavy loads, require an expensive, functionally secure rotary support of the hook, such devices are extremely unsatisfactory in view of the fact that at faulty function due to faulty operation or breakage of some of the details which in the lifting position lock the pivotable hook, the load is directly released because the load suspended on the hook continously tends to turn the hook into the released position.